Brushless direct current electric motors (BLDC motors) include a stator provided with windings, a rotor provided with permanent magnets, and a controller configured to supply power to the stator. The stator of a known BLDC motor includes a stator core, and windings wound around the stator core. The windings include M phase windings, each phase winding includes a plurality of parallel branches. When one branch of one phase winding is disconnected, an unbalance occurs between that phase winding and the other phase windings, which causes a high torque ripple of the electric motor, resulting in high vibration. Particularly, when a brushless direct current electric motor of a power steering system for steering a vehicle breaks down, if the driver turns the steering wheel, the windings may short circuit and generate a short circuit current, thereby generating a retarding torque to hinder the rotation of the steering wheel. Therefore, the known BLDC motor has a potential safety hazard.